Conventionally, when a group of figures (drawing) produced by a CAD/CAM system or the like are drawn by an XY plotter, a rectangular drawing subject region (hereinafter referred to as CRT drawing) including a figure group F1" (FIGS. 7 and 8) drawn on the screen of a graphic display device is specified by manually inputting the lengths Xmax and Xmin thereof in positive and negative directions of the X axis and the lengths Ymax and Ymin thereof in positive and negative directions of the Y axis to an information processor of the CAD/CAM system through a tablet, a keyboard, and the like. The ratio (plotting scale) of the dimensions of the drawing which is to be drawn by the plotter (hereinafter referred to as plotter drawing) to the dimensions of the CRT drawing is also manually input through the keyboard. Further, to plot the CRT drawing at a suitable place on plotter paper with the former being correlated with the latter, a coordinate position (x0, y0) in the xy coordinate system of the XY plotter, which, for example, corresponds to a CRT drawing origin P" represented by the origin (0, 0) of the XY coordinate system of the CRT screen, is manually input through the tablet or the like. Subsequently, a drawing command is input through the tablet, whereby the CRT drawing is plotted in a predetermined drawing area of the plotter paper 100 on a predetermined scale by the XY plotter under the control of the information processor so that the origin P" of the CRT drawing coincides with the coordinate position (x0, y0) of the plotter coordinate system (FIG. 7). In FIG. 7, symbol F2" denotes a figure group drawn on the plotter paper.
When, instead of manually inputting the plotting scale, an automatic scale setting mode is selected, the information processor automatically sets a maximum scale for plotting the CRT drawing on the plotter paper 100 on the largest possible scale, in accordance with the size of the plotter paper and the dimensions of the CRT drawing, and the XY plotter reproduces the drawing on the maximum scale (FIG. 8).
According to the above-described conventional methods, however, an operator is required to calculate the coordinate position (x0, y0) in the plotter coordinate system corresponding to the CRT drawing origin P", and to manually input the calculated values to the CAD/CAM system. If the calculation or the manual inputting of the origin is erroneous, the CRT drawing cannot be plotted in the required area of the plotter paper 100, or even the whole of the CRT drawing cannot be drawn on the plotter paper.